OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
FORMULA
Equals {0,1} union A025583.
MATHEMATICA
f[n_] := (p = 0; pn = PrimePi[n]; Do[If[n == Prime[i] + Prime[k], p = p + 1; If[p > 2, Break[]]], {i, 1, pn}, {k, i, pn}]; p); Join[{0, 1}, Select[Range[2, 6000], ! PrimeQ[#] && f[#] == 0 &]] (* G. C. Greubel, Sep 18 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Aug 14 2009
EXTENSIONS
Comment turned into formula by R. J. Mathar, Aug 20 2009
STATUS
approved